2009 RMAG Petra Tips and Tricks Short Course_Working With Log Data

8/11/2019 2009 RMAG Petra Tips and Tricks Short Course_Working With Log Data

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BobCluff

TheDiscoveryGroupInc.

RMAGSpringshortcourse,

20April2009


2/43

ObjectivesWeassumeyoualreadyknowhowtousethe

software,

Ourgoalistopresentaseriesofusertipsandtricks

that

will: Improveworkflows

Letyoudothingsthatmaynothavebeenobvioushow

to

do Workaroundlimitationsinthesoftwareorsubstitute

forfeaturesthatarenotexplicitlydesignedintothe

package Generallysaveyoutime,effort,andmoney


3/43

Loganalysistipsandtricks Petrahasageneralpurpose,flexiblelogcalculationengine

builtinto

it.

ItdoesNOTaimtobeahighendpetrophysicalmodelingormodeldevelopmentpackage

DISCLOSURE:DiscoveryGroup

does

not

attempt

to

force

fit

Petraintothatmold,wehaveseveralspecializedpetrophysicspackagesavailableforourworkflows

WeDOusePetraforbatchprocessingoflargenumbersof

wells,for

computing

pore

volumes

and

HCPV

over

entire

fields,andforitsintegrationwithcrosssections,mapping,andotherwelldata

WeuseitEVERYDAYinourpetrophysicalstudies


4/43

WhatPetradoeswellManageandorganizelogdata,includingsupportfor

logaliases

Allowyoutosplicecurvesorlogruns,editcurves,&performsomebasiccurvenormalization

Computeshaliness,

porosity,

and

fluid

saturations

Computeflagcurvesusingavarietyofcriteria

Computenetpay,netofuserdefinedcutoffs

Runprocessesonlargenumbersofwellsveryquickly

Allowsyoutowriteandsaveflexibleuserequations,

and

to

some

extent

user

programs


5/43

WhatPetradoesnotdo..Runvendorandtoolspecificenvironmental

correctionsSupport1or2pointnormalizationusinghistogram

overlays at

least

without

using

aprinter

and

alight

table

Usestandardcrossplotroutinestocomputeporosityfrommultiplelogs(e.g.neutrondensity)

Computemulti

mineral

volumes

(e.g.

Vdol

Vls

Vqtz)

Linktooutsidecodesinstandardlanguages(e.g.VisualBasic,C++,Java,etc.)


6/43

LeftforanotherdayNormalization

Crossplotting

Multimineralmodels

TheAdvancedUserModels language


7/43

A.How

do

Ibring

log

data

into

Petra,

and

what

are

the

pitfallsofusingthebatchLASimportfunction?

APInumberscritical,cantlivewithem,cantlivewithout

em

WrongAPI=WrongassociationwithawellinPetra.

Youcannot

assume

the

vendor

or

digitizer

got

it

right.

Solutions:

Importwellsoneatatime

Openeach

LAS

file

in

atext

editor

and

add/fix

them

ExtracttheAPInumbersfromtheLASfiles,edittheminaspreadsheet,writethembackintotheLASfiles.


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B.

Howdo

Iimport

LAS

header

data

to

Petra,

and

what

arethedifferencesbetweenLAS1.2and2.0formats?

LAS1.2and2.0headersuseadifferentformatfortheWell

information

block,

including

information

such

astheAPInumber

PETRArecognizesbothformats,andautomaticallyflipsthem

into

the

standard

(2.0)

order

Thecriticaldatatocaptureareanythingusedinlog

calculations

or

useful

for

log

evaluations Loggingdate,runnumber,andservicecompany

Mudtype,weight,Rm@T___,Rmf@T___

Maxrecorded

temperature,

LTD,

base

of

csg


10/43

LAS version 1.2 Well Information Section.~Well Information Section

#MNEM.UNIT Data Type Information#--------- ------------- ------------------------------

STRT.M 635.0000:

STOP.M 400.0000:

STEP.M -0.1250:

NULL. -999.25:

COMP. COMPANY: ANY OIL COMPANY INC.

WELL. WELL: ANY ET AL A9-16-49-20FLD . FIELD: EDAM

LOC . LOCATION: A9-16-49-20W3M

PROV. PROVINCE: SASKATCHEWAN

SRVC. SERVICE CO: ANY LOGGING COMPANY INC.

DATE. LOG DATE: 13-DEC-86

UWI . UNIQUE WELL ID: 100091604920W300

LAS version 2.0.

~Well Information Section#MNEM.UNIT VALUE/NAME DESCRIPTION

#-------- -------------- ---------------------

STRT.M 635.0000 :START DEPTH

STOP.M 400.0000 :STOP DEPTH

STEP.M -0.125 :STEPNULL. -999.25 :NULL VALUE

COMP. ANY OIL COMPANY INC. :COMPANY

WELL. ANY ET AL 12-34-12-34 :WELL

FLD . WILDCAT :FIELD

LOC . 12-34-12-34W5M :LOCATION

PROV. ALBERTA :PROVINCE

SRVC. ANY LOGGING COMPANY INC. :SERVICE COMPANYDATE. 13-DEC-86 :LOG DATE

UWI . 100123401234W500 :UNIQUE WELL ID

Lookat

the

order

of

the

Data

TypeandInformationinanLAS1.2header

vs.theorderinanLAS2.0header. Theorderisnowconsistentinalldatablocks


11/43

Headersareimportedseparately,andtheheaderimport

will

create

anew

well

ifit

cannot

find

an

API

numbermatch

The

mapping

between

header

data

and

zone

data

fieldsisvendorspecificwithafewexceptionstheLASstandarddoesnotspecifyparameterorcurvemnemonics. Loggingcompaniesanddigitizerscookuptheirownabbreviations!

Youcansavethemappingforreuse.

Ithas

to

already

exist

to

be

used

in

abatch

import.


12/43

1.2file

2.0file


13/43

C.How

do

Iuse

curve

name

aliases,

and

how

should

theybeorganized?

Aliasesarepublicandprojectwide.

Aliasesare

NOT

nested.

Youneedtolistcurvesinthehierarchyyouwantthemtobeused. E.g.,ifyouwanttouse2ftresolution

resistivitycurves

in

preference

to

1ft

curves,

put

them

higherinthelist.

Werecommendeither:

Usethe

most

common

curve

names

as

your

aliases

(GR,

NPHI,DPHI),andaliasallthesynonymstothem;or

SetupspecialaliaseslikeALIAS_GR soitisobvious

which

are

the

aliased

curve

names


14/43

SincePetra

uses

the

firstcurveitfindsinanaliaslist,ifyou

havemultiple

runs

withdifferentcurvenamesyouwillneed

tosplice

runs

to

createasinglecurvethatappearshigher

inthe

alias

list


15/43

D.

Ihave

way

too

many

curve

names

how

can

Iclean

itupandsimplifymycurvedatabase?

Deanalreadytalkedaboutthis.

Weexport

the

curve

listing,

with

well

counts,

to

aspreadsheet

before

anyseriousorganizing Ithelpstocategorizecurvesbyloggingvendor,tooltype,vintage,&

datasource Usesuffixesandprefixestosetapartspecialcurveclasses(flags,

aliases,normalized

curves,

etc.)

Consideradjective/nounorder. Thereisareasonthemilitarynamesthingsthewaytheydo!

Weliketopreserveoriginalloggingvendormnemonics,thereisoften

informationin

them

that

might

not

be

obvious

to

anon

specialist

e.g.anAtlasCNCandCNCFaredifferent Porositylogsareonlyusefulwhenyouknowthematrixassumptions

(SS,LS,DOL),makethempartofthename!


16/43


17/43

E. Myporositylogsarevariouslyindecimal(v/v)and

percent(pu)

units.

How

do

Iclean

that

up

so

they

plot

correctlyoncrosssectionsandcomputesaturations

right?

Findthemallfirst Easiesttocomputelogstatisticsandthenusewell

select

by

data

criteria

functionConvertthemalltothesamebasis. Mostequations

wantfractionalporosity.

Recomputethe

stats

and

check

your

work

Pitfall:logrunchangeswithdifferentvendors. Thisisacleanupproblemthatneedstobefixedwhencurves

are

spliced.


18/43

F. Someofmywellshavedensityporosity,othershave

bulkdensity,

some

both,

what

should

Iuse

and

how

do

Igetthemallonacommonbasis?

Asbefore,

find

them

first

using

the

well

select

by

data

criteriafunctions.

DensityporositycurvesareALWAYSambiguous,

sincethey

made

amatrix

density

and

fluid

density

assumptioninthefieldwhencurvewascomputed LASheadersrarelyrecordthesevalues.Youhaveto

lookthemuponthepaperlogs/rasters.

Bewareofmidlogscalechanges

Enterthevaluesaszoneparameters;wesetupaspecialpetrophysics orlogging zoneforthisandotherdata.


19/43


20/43

G. SomeofmywellshaveneutronporosityinLSunits,

othersare

in

SS,

what

should

Iuse

and

how

do

Iget

themallonacommonbasis?

EqnstoconvertfromLSSSandSS LSarenotpublished

by

the

service

companies

Youcandigitizethechartbooksandfiteqnstothecurvesyourself

LSunitsarethetruebasisofneutronlogging. Othermatrices

are

output

as

aconvenience

for

log

analysis

on

thehoodofaChevy Therelationshipsareallnonlinearexceptinlimestone.

They

vary

from

company

to

company,

tool

to

tool. Findingproblemwellsisdifficultbecausethemnemonics

generallydonotincludethematrix. Lookthemuponthepapercopies

Plotspecial

xsections

and

look

for

distinctive

separation


21/43


22/43

20%

25%

Highendpackagescomputebothporosityand%mineralvolumesbasedoninterpolationofisoporositylinesandmineralendpoints

SS

LS

SH


23/43

Usefulresources(outsidePetra)

Didger4.0 onscreendigitizingsoftwarefromGolden

Software

Grapher7.0has11predefinedcurvefittingalgorithmsthatfitmostcommonchartbookcurves

Excelhasverybasiccurvefittingfunctionality;youcanalsopurchaseanaddinthatexpandsonthis

At

the

high

end,

TableCurve2D

and

TableCurve3D

fit

thousandsofpredefinedfunctionstoadataset

Learnsomelinearalgebraifyouwanttodoit

yourself


24/43

H. WhatisthebestwaytobringcoredataintoPetra,

andwhat

should

go

into

the

core

tab

vs.

what

goes

into

thelogcurvedatabase?

Coredata

live

in

two

places

in

Petra:

TheCoresTab,whichstoresinformationoncoretype,coredinterval,datecored,recovery,etc. Thiscanbe

posted

on

logs

and

sections TheLogstab,whereactualnumericalcoredatais

storedwiththelogdata

Coredata

can

be

imported

as

LAS

or

as

ASCII

files,

depthshifted,plotted,andmanipulatedlikeanylogdata


25/43

Coredepth

shifts

can

be

recorded

on

the

Cores

tab,orasremarkstoeachcurveintheLogtab

Theseare

global

remarks

(applies

to

the

curveinallwells


26/43

Thesearelocalremarks


27/43

I. Howdo

Ideal

with

data

on

different

depth

increments(e.g.0.5ftlogdataand1ftcoredata)?

Petraisdatabaseoriented,nottiedtoaspecificframe

incrementlike

an

LAS

file

Itallowsdataondifferentdepthstepstocoexist

TheproblemariseswhenyouEXPORTdatatoanLASfile,becauseLASfilesrequireaspecificstepvalue

Petrawillnotresamplecurvesonthefly,butitwill

allow

you

to

only

export

data

with

a

specific

sample

rate


28/43


29/43

Bestsolutionistoresamplecurvespriortoexport

usingLogTransformationsTransformsResample

curves

Note:thisfunctionOVERWRITEStheoriginalcurve,so

youmight

want

to

work

on

acurve

copy

Also,becarefulwhenresamplingcoredata,asinterpolatedvaluesmightnotbewhatyouwant


30/43

Usewithcoredata!


31/43

J.

Whatis

the

easiest

and

cleanest

way

to

splice

curves,nullbaddata,toolpickup,etc.inPetra?

EasiestisintheLogCurvePreviewer,accessedfrom

theLogs

tab

Youcannullsections,smooth,anddespikecurvesallinthispanel

CurvesplicingisdoneinLogs SpliceCurves


32/43


33/43

K.

Iwant

to

baseline

shift

all

my

SP

logs

so

they

are

at

~0mValongtheshalebaseline.WhatdoIdo?

Thisisquickifyoujustneedabasicbaselineshift

Startby

cleaning

up

the

curves,

including

nulling

tool

pickupandintervalsbehindcasing

Ifyoudont,thosesectionswillbecountedinthelogstatisticsandcouldskewyourbaseline

Fixanyobviousoffsetsbetweenloggingruns

Compute FromLogs Statistics,

and

calculate

the

95th percentileoftheSPusingthearithmeticmean.Savethisinanappropriatezone(likePetrophysics)


34/43


35/43

UsingCompute FromLogsEquationExpression, SP_BLS

=SP

PC95SP

AssingtheappropriatecurvenametoSP,usingaliasesifnecessary,andassignthezoneparametercalculated

beforeto

PC95SP

AllofyourSPlogswillbebaselineshiftedtoavalueofzeroatthe95th percentile.

This

does

not

correct

for

drift

with

depth,

it

is

asimplebaselineshift.

Unlikethenormalizationfunction,thisdoesnot

rescale

the

SP

curves

it

is

just

an

offset

correction.


36/43

L. Whatis

meant

by

net

pay and

how

do

Icompute

it

inPetra?

Petrasnetpay moduleisactuallyageneralpurpose

summation

module,

accessed

via

Compute

FromLogs

Footages(ReservoirProperties). ItisoneofPetrasgreateststrengths.

Definitions:

GROSS=the

total

interval.

Calculated

using

the

Compute

FromZones Isopachfunction. GROSSSAND=sandnetofashaliness(GR)cutoffonly,set

byCondition4intheLogFootageSummationscreen.

NETSAND

=sand

net

of

shaliness

and

porosity

cutoffs,

ignoringfluidsaturation. Thisissetbyconditions1and4inPetra. Engineerswantthistodefinethetotalcontainervolume.


37/43

NETPAY=sandstonenetofshaliness,porosity,and

watersaturation

cutoffs.

Petra

also

adds

aPermeability

conditionandaUserLogcondition,forexampleaflagcurvetoexcludecertainlithologies(e.g.coal)

Because

Petra

defines

net as

passing

ALL

checked

conditions,youneedtobecareful. Ifyouwanttocalculatenetporevolume,irrespectiveofSw,youcannotchecktheSwcondition,orelseyouhaveto

openup

the

cutoff

range.

Weoftenrunthismoduletwice,oncetogetreservoirvolumes,asecondtimetogetnetpay volumes.


38/43

Firstrungetsnetreservoir

properties

Secondruncomputespay properties


39/43

Youcancreateflagcurvesinthismoduleonthe

Capturetab

YoucansavepredefinedsetupscreensastemplatesandruntheminBatchmodetodomorethanonestep,

or

calculate

net

pay

sensitivity

to

some

key

criteria

e.g.netpay>6%,>8%,and>10%


40/43

M.HowdoIcomputeSwonalargenumberofwells

overabig

area

where

some

key

parameter,

like

Rw,

variesfromwelltowell?

You

have

two

choices:

Runeachzoneindividuallyusingequationexpressions,whichcanbesavedinyourequationlist.


41/43

Or,use

the

ComputeFromLogsAdvancedLog

TransformsUserModelLogTransformmodule.

ProgramminglanguageissimilartoBasicandis

undocumented.

Onlythe

examples

provided

with

Petraserveasaguidetowhatcanbedone.

GOTO,IFTHEN,BEGINENDandDONEstatements

Allinput

logs,

constants,

and

output

logs

are

declared

atthestart. Ifthemodelcompiles,yougetascreenthatallowsyoutoassignallofthosetologsorzone

parametersin

Petra.

Youcanrunthemodeloverselectedzonesortheentirewell.


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Documents

2009 RMAG Petra Tips and Tricks Short Course_Working With Log Data